Integrated circuits devices are typically housed in packages. Typical packages are made of plastic, ceramic, or metal. The packages include internal and external conductive structures, such as metallized vias, metal traces, bond wires, and solder interconnection balls or leadless chip carrier ("LCC") pads, for electrically connecting the integrated circuit device in the package to external circuitry, such as a circuit board.
Certain types of integrated circuit devices, such as erasable programmable read-only memory devices ("EPROM"), charge coupled devices ("CCD") or optical sensing devices, such as those used in document scanners, fingerprint recognition equipment, or other consumer products, require a selected or continuous transmission of light of a selected frequency through the top surface of the package onto the surface of the integrated circuit die within the package. Typically, the packages for such integrated circuit devices have a glass or quartz window in the otherwise opaque top surface of the package. This transparent window is located above the die, and the selected frequency of light passes through the window and impinges on the top surface of the die. Unfortunately, packages having such glass or quartz inserts are relatively expensive to fabricate, which raises the cost of the products in which the integrated circuit devices are used. A less expensive alternative would have wide application.